In a report critical of Environmental Protection Agency (EPA) research policies, the EPA Office of Inspector General, said the EPA failed to disclose cancer risks to volunteer subjects in research studies on harmful pollutants.

The EPA warns the public of the dangers from diesel exhaust and tiny particles in the air, but when the agency recruited people for tests on those pollutants in 2010 and 2011, the subjects’ consent forms did not mention cancer, according to the report issued yesterday. The agency considered the risks from short-term exposure minimal, Bloomberg News reports.

Republican legislators, including Louisiana senator David Vitter, have criticized EPA regulations themselves and the agency’s research practices, saying particulate-exposure rules and warnings are at odds with EPA testing practices. Some have called for human testing to be shut down, Bloomberg News reports. The inspector general’s report said the EPA followed “applicable regulations” in the recent studies, but the agency should “inform study subjects of any potential cancer risks of a pollutant to which they are being exposed.”

In the past ten years, the EPA has conducted four studies of diesel exhaust and 13 studies of particulate matter at its North Carolina laboratory. In these studies, 20 to 40 volunteers spent time in a chamber where pollution levels similar to those in Los Angeles or New York were created. Subjects’ heart, lung, and blood functions were monitored for about two hours. The EPA says long-term health effects are unlikely because the test period was so short. Pollutant exposures in the tests “reflect a balance between being high enough to produce biological responses but not so high as to produce clinical responses,” according to Bloomberg News. Such studies have been conducted for more than 40 years and they provide detailed data on how pollutants affect individuals, the EPA says.

Bob Kavlock, a deputy assistant EPA administrator for science, wrote in a blog post that the agency is “in the process of embracing [the] recommendations.” He praised the volunteers for their “generous spirit” and “contribution of time,” and said they “play a vital role in helping EPA scientists advance the cause of protecting the health of all Americans,” according to Bloomberg News.